Apex domains cannot have CNAME records.
Question and response
Question
dig link11.de. NS
Answer
link11.de. 5 NS ns2.link11.de.
link11.de. 5 NS ns3.link11.de.
link11.de. 5 NS ns1.link11.de.
Authority
The response has no authority records.
Additional
ns1.link11.de. 5 A 85.131.129.7
ns2.link11.de. 5 A 128.65.208.70
ns3.link11.de. 5 A 31.214.215.5
ns1.link11.de. 5 AAAA 2001:4d50:10:0:0:0:0:2
ns2.link11.de. 5 AAAA 2001:4d50:10:1:0:0:0:2
ns3.link11.de. 5 AAAA 2001:678:3a8:0:0:0:0:5
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0